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Comparative studies of natural groups of organisms

structures known as basidia from (b) Hyphae having septa with distinctive
which haploid, sexually reproduced pores.
spores (basidiospores) are produced.
(b) Sexual reproduction in most Structure of Agaricus
basidiomycetes results into the Members of Agaricus consist of a stalked
formation of dikaryotic hyphae fruiting body with pileus on its top (a
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(c) They have septate hyphae. fleshy cap), which in turn bears numerous
(d) Some basidiomycetes are saprophytes, radially arranged gills on its basement.
while others are parasites. The vegetative mushroom body is also
called mycelium. The underground
Distinctive features of phylum hyphae have minute thin filaments called
Basidiomycota rhizoids, which are collectively as a group
Members of phylum Basidiomycota known as mycelium threads. They are
possess some features that differentiate located underneath the fruiting body, and
them from the other phyla. These features they store and supply the nutrients to the
include: mushroom. These structures anchor the
(a) Presence of basidium formed at the tips of mushroom to the substrate, while the stipe
hyphae which is a characteristic sexual (stem) make it stand upright (Figure 3.21).
spore producing structure in which Cup (volva) is found below the stem while
union of dikaryotic nuclei occurs, the ring (annulus) surrounds the stem.
followed by meiosis to produce
haploid basidiospores.

Cap (pileus)

Ring (annulus) Gills (lamellae)

Stem (stipe)

Cup (volva)

Mycelium
(rhizoids)

Figure 3.21: Structure of an Agaricus

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